#include <iostream>
using namespace std;

// 分别利用普通写法和多态技术实现计算器
// 普通写法
class Calculator{
public:
    int m_Num1;
    int m_Num2;
    int getResult(string oper){
        if (oper == "+"){
            return m_Num1 + m_Num2;
        }else if(oper == "-"){
            return m_Num1 - m_Num2;
        }else if(oper == "*"){
            return m_Num1 * m_Num2;
        }
        // 如果想扩展新的功能，需要修改源码
        // 在真实的开发中，提倡开闭原则
        // 开闭原则：对扩展进行开放，对修改进行关闭
    }
};
void test01(){
    // 创建计算器对象
    Calculator c;
    c.m_Num1 = 10;
    c.m_Num2 = 20;
    cout << c.m_Num1 << "+" << c.m_Num2 << "=" << c.getResult("+") << endl;
    cout << c.m_Num1 << "-" << c.m_Num2 << "=" << c.getResult("-") << endl;
    cout << c.m_Num1 << "*" << c.m_Num2 << "=" << c.getResult("*") << endl;
}

// 利用多态实现计算器
// 多态好处：
// 1、组织结构清晰
// 2、可读性强
// 3、对于前期和后期扩展以及维护性高
// 实现计算器抽象类
class AbstractCalculator{
public:
    int m_Num1;
    int m_Num2;
    virtual int getResult(){
        return 0;
    }
};
// 加法计算器类
class AddCalculator:public AbstractCalculator{
public:
    virtual int getResult(){
        return m_Num1 + m_Num2;
    }
};
// 减法计算器类
class SubCalculator:public AbstractCalculator{
public:
    virtual int getResult(){
        return m_Num1 - m_Num2;
    }
};
// 乘法计算器类
class MulCalculator:public AbstractCalculator{
public:
    virtual int getResult(){
        return m_Num1 * m_Num2;
    }
};
void test02(){
    // 多态使用条件
    // 父类指针或者引用指向子类对象
    AbstractCalculator * abc = new AddCalculator;
    abc->m_Num1 = 10;
    abc->m_Num2 = 20;
    cout << abc->m_Num1 << "+" << abc->m_Num2 << "=" << abc->getResult() << endl;
    // 用完后记得销毁
    delete abc;

    // 减法运算
    abc = new SubCalculator;
    abc->m_Num1 = 10;
    abc->m_Num2 = 20;
    cout << abc->m_Num1 << "-" << abc->m_Num2 << "=" << abc->getResult() << endl;
    delete abc;

    // 乘法运算
    abc = new MulCalculator;
    abc->m_Num1 = 10;
    abc->m_Num2 = 20;
    cout << abc->m_Num1 << "*" << abc->m_Num2 << "=" << abc->getResult() << endl;
    delete abc;
}
int main(){
//    test01();
    test02();
}